Soil remediation method

ABSTRACT

The present invention relates generally to a soil remediation method, and more particularly to a soil remediation method relying on the chemical oxidation of organic contaminants in saturated or unsaturated soil and aided by mechanical agitation of the soil. The method may be carried out in ex-situ or in-situ schemes per the devices disclosed herein.

This application is a continuation-in-part of U.S. application Ser. No. 08/964,459, filed Nov. 4, 1997 now U.S. Pat. No. 5,988,947.

FIELD OF THE INVENTION

The present invention relates generally to a soil remediation device, and more particularly to a multi-section soil remediation device having at least one section for applying a variety of soil treatment regimes. The multi-section device can be adapted to mount to a vehicle for operation in the field.

BACKGROUND OF THE INVENTION

It is widely recognized that years of industry has produced numerous environmentally hazardous sites throughout the country and the world which pose substantial health hazards to the world's population. In recent years, efforts to clean up or remediate environmentally contaminated sites have increased dramatically. Numerous methods and devices for cleaning up or disposing of environmental contamination in water, air, and soil have been devised. The magnitude of the environmental contamination is enormous in comparison to the resources made available to solve this problem.

To address the problem of environmental contamination and particularly soil contamination, a variety of soil treatment and decontamination techniques have been developed. These techniques involve, but are not limited to the application of fluids, biological agents, heat, vacuum, pressurized gases, and mechanical agitation. In order to remediate contaminated soil, it is often necessary to apply several different treatment techniques either alone or in some combination and order that is usually determined by the particular contaminate or contaminates under remediation.

As a consequence, there is an urgent need for a device that can be easily adapted in the field to apply a variety of treatment techniques. This device should be relatively uncomplicated, rapidly configured and assembled in the field, and cost effective. The present invention addresses and solves many of the above-mentioned problems associated with currently available systems.

SUMMARY OF THE INVENTION

The present invention relates to a multi-section soil remediation device having at least one section for applying a variety of soil treatment regimes. The multi-section device can be adapted to mount to a vehicle for operation in the field.

The multi-section device includes at least two soil remediation chambers each having an inlet, an outlet, and a soil conveyor for conveying soil from the chamber inlet to its outlet. The soil remediation chamber is arranged such that the outlet of at least one remediation chamber feeds soil into the inlet of at least one other remediation chamber. The multi-section device also includes a soil treatment delivery system connected to and in communication with at least one of said soil remediation chambers. The soil treatment delivery system delivers soil treatment to the soil that is conveyed within the soil remediation chamber.

It is an object of this invention to provide a multi-section soil remediation device that is relatively uncomplicated, rapidly configured and assembled in the field for applying various treatment techniques in cost effective manner to remediate environmentally contaminated sites. It is another object of this invention to provide a highly mobile apparatus for remediating environmental contaminants. It is yet another object of this invention to provide a method of remediating contaminated soil in situ and without removal or disposal of the treated or contaminated material to a remote location. It is yet another object of the invention to provide a method that is capable of remediating contaminated soils and sludge in a continuous manner.

BRIEF DESCRIPTION OF THE DRAWINGS

For the purpose of illustrating the invention, there is shown in the drawings a form which is presently preferred; it being understood, however, that this invention is not limited to the precise arrangements and instrumentalities shown.

FIG. 1 is an illustration of a multi-section soil remediation device as contemplated by the present invention.

FIG. 2 is an illustration of a multi-section soil remediation device as contemplated by the present invention having an alternate soil conveying mechanism.

FIG. 3A is an illustration of a multi-section soil remediation device as contemplated by the present invention shown attached to a vehicle.

FIG. 3B is an illustration of a multi-section soil remediation device as contemplated by the present invention having an alternate discharge arrangement.

FIG. 3C is an illustration of a multi-section soil remediation device as contemplated by the present invention having a horizontal arrangement of elements and shown attached to a vehicle.

FIG. 4 is an illustration of a portion of the multi-section soil remediation device as contemplated by the present invention having a magnetohydrodynamic apparatus for soil remediation.

FIG. 5 is an illustration of a portion of the multi-section soil remediation device as contemplated by the present invention having a laser apparatus for soil remediation.

FIG. 6 is an illustration of a multi-section soil remediation device as contemplated by the present invention having an alternate arrangement of elements and shown attached to a vehicle.

DETAILED DESCRIPTION OF THE INVENTION

The present invention is a multi-section soil remediation device having at least one section for applying a variety of soil treatment regimes. The multi-section device can be adapted to mount to a vehicle for operation in the field.

Referring now to the drawings, wherein like numerals indicate like elements, there is shown in FIG. 1 a multi-section soil remediation device 10 as contemplated by the present invention. The multi-section soil remediation device 10 includes a plurality of soil remediation chambers 20. Each chamber 20 a, 20 b, 20 c having an inlet 60, an outlet 70, and a soil conveyor 80 therein for conveying soil from the chamber inlet 60 to its outlet 70. The soil remediation chambers 20 being arranged such that the outlet 70 of at least one remediation chamber feeds soil into the inlet 60 of at least one other remediation chambers 20.

The inlet 60 of one soil remediation chambers 20 is designed to fit within the outlet 70 of another soil remediation chambers 20. For example, the shape of the inlet 60 and outlet 70 are matingly frustoconical such that one fits within the other forming a tight seal. The seal can be further enhanced by form gaskets or elastic collars. The soil remediation chambers 20 are typically arranged in a vertical orientation and supported by a frame that maintains the position of the soil remediation chambers 20 and the seal between the inlet 60 and outlet 70. However, it is understood that the arrangement of the soil remediation chambers 20 can be in any orientation including vertical, horizontal, or some combination thereof. In addition the form, mating, and seal between the inlet 60 and outlet 70 of two soil remediation chambers 20 can also be varied in shape and material.

The multi-section soil remediation device 10 also includes a soil treatment delivery system 40 having a plurality of treatment delivery elements 40 a, 40 b, 40 c connected to and in communication with at least one of said soil remediation chambers 20 for delivering soil treatment to soil conveyed within the soil remediation chambers 20. The soil conveyor 80 is powered by a commercially available drive system 85 such as, but not limited to, a gear and chain arrangement powered by a gas or diesel engine or hydraulic motor (not shown).

In one aspect of the present invention as shown in FIG. 1, the soil remediation chambers 20 are preferably cylindrical tubes. However it is understood that the soil remediation chambers 20 are not limited to cylindrical tubes and can be any shape such as, but not limited, to oval or rectangular. The chambers 20 have a screw-type conveyor 80 that is operative within the cylindrical tubes 20 a, 20 b, 20 c and move the soil received through the inlet 60 until discharged through the outlet 70 by the cylinders 20 a, 20 b, 20 c.

In another aspect of the present invention as shown in FIG. 2, the chambers 20 have a belt-type conveyor 90 that is operative within the cylindrical tubes 20 a, 20 b, 20 c. The belt-type conveyor 90 moves the soil received by the inlet 60 so that it can be discharged through the outlet 70. The soil is treated as it is conveyed through the cylindrical tubes 20 a, 20 b, 20 c by materials injected in and removed from the tubes by the treatment delivery system 40.

In another aspect of the present invention as shown on FIG. 3A, the soil remediation chambers 20 of the multi-section soil remediation device 10 are arranged in a vertical plane and supported by a frame 240 attached to a track vehicle 200. In this aspect of the multi-section soil remediation device 10, the conveyors (not shown) are powered by equipment on the track vehicle 200. The soil is fed into the inlet 60 of the soil remediation chambers 20 where it is remediated and discharged through the outlet 70. It is understood that the location of the inlet 60 and outlet 70 can be anywhere on or near the track vehicle 200. For example, FIG. 3A shows the outlet the soil remediation chamber 20 c to be within the body of the track vehicle 200. In another example, FIG. 3B shows the outlet the soil remediation chambers 20 c to be outside the body of the track vehicle 200.

In another aspect of the present invention as shown in FIG. 3C, a multi-section soil remediation device 10 is shown having a horizontal arrangement of soil remediation chambers 400 also shown attached to a vehicle 480. The conveyors (not shown) within the soil remediation chambers 400 are powered by a power unit 430 on the track vehicle 480.

In all aspects of the present invention, the multi-section soil remediation device 10 includes a soil treatment delivery system 40 adapted to inject or extract, individually or in combination, solid, liquid, or gaseous soil treatment compounds, at a selected temperature, into, or from, the soil remediation chambers 20,400.

For example, the soil treatment delivery system 40 shown in FIG. 3B includes a vapor, liquid and solid emission recovery system 310 for recovering vapor emissions produced in the soil remediation chambers 20. Soil treatment delivery systems and emission recovery systems are described in greater detail in U.S. Pat. No. 5,631,160 and U.S. application Ser. No. 08/693,629, invented and owned by the present inventor and are incorporated herein by reference.

In FIG. 3B the emission recovery system 310 can recover emissions such as, but not limited to, vapor, liquid and solid produced or remediated in the soil remediation chambers 20. The emission recovery system 310 includes, but is not limited to, a thermal oxidation system or an activated carbon system. For example, thermal oxidation systems such as flameless oxidizers for VOC and HAP control are made by Thermatrix Inc. can be incorporated directly into a remediation chamber 20 or added at any point along or between a remediation chamber 20.

In one aspect of the present invention the emission recovery system 310 has a hydraulic power source 210 which includes a combustion engine, a hydraulic pump driven by the engine and a hydraulic reservoir for storing and supplying hydraulic fluid to the hydraulic pump. It is understood that the power source need not be hydraulic and can be provided by a power source that is external to the multi-section soil remediation device 10.

The power source 210 may further include ancillary hydraulically powered appliances and related attachments including, but not limited to: fluid pumps, air blowers, fluid storage containers, and air treatment canisters 220. The power source further includes a hydraulic distribution system which directs the hydraulic power to the ancillary appliances of the power unit and to the auxiliary equipment associated with the vehicle. The distribution system may be separate from or incorporated with the hydraulic pump. The power source 210 may further include a control console (not shown) and related circuitry adapted for mounting on a vehicle in proximity to its operator. The control console is used to control and operate the ancillary appliances of the power source 210 and the auxiliary equipment associated with a vehicle 200.

In another aspect of the present invention as shown in FIG. 4, a portion of the multi-section soil remediation device 10 as contemplated by the present invention has a magnetohydrodynmic plasma apparatus 200 for soil remediation. The magnetohydrodynmic plasma apparatus 200 has a probe 250 that allows plasma energy to contact and treat the soil on a conveyer 90 within the soil remediation chambers 20. It is contemplated that plasma devices such as Arc Plasma Systems and Induction Coupled Plasma (ICP) technology would be used by the present invention. An example of one such ICP system is described in Plasma Technology, Inc., Induction Coupled Plasma (ICP) in Comparison with ARC Plasma Systems An Introduction, and is incorporated herein by reference.

It is also contemplated that soil remediation can be accomplished by other processes such as biodegradation, hot air injection, and/or the use of phosphate or carbonate sources. For example, degradation of coal tar and its constituents can be accomplished by white rot fungi or by phanerochaete chrysosporium as described in U.S. Pat. Nos. 5,597,730 and 5,459,065, respectively and are incorporated herein by reference. Hot air injection can be accomplished by utilizing the exhaust heat that is generated by engines on-board or in proximity to the invention. In another example, remediation of soils or slurries containing heavy metals such as arsenic, cadmium, chromium, copper, lead, or zinc can be accomplished by applying phosphate, carbonate or sulfate sources as described for example in U.S. Pat. Nos. 5,202,033, 5,037,479 and 4,889,640 and are incorporated herein by reference.

In yet another aspect of the present invention as shown in FIG. 5, a portion of the multi-section soil remediation device 10 as contemplated by the present invention has a laser apparatus 100 for soil remediation. The laser apparatus 100 has an aperture 150 that allows laser energy to contact and treat the soil in the conveyer 90 with in the soil remediation chambers 20. It is contemplated that laser devices such as, but not limited to, a LUMONICS Corporation MW3000 focus head would be used by the present invention.

Multiple laser apparatus 100 and magnetohydrodynmic plasma apparatus 200 can be mounted to the soil remediation chambers 20. These apparatus can be positioned to provide 360° area coverage of laser or plasma energy on the soil as it is conveyed through the soil remediation chambers 20. The laser apparatus 100 and magnetohydrodynmic plasma apparatus 200 can be mounted on one or all of the soil remediation chambers 20 as needed to ensure complete treatment of the soil.

Power for the laser apparatus 100 and magnetohydrodynmic plasma apparatus 200 can be supplied by the power source 210 as shown in FIG. 3A. It is recognized that laser and plasma treatment can induce extremely high temperatures within the soil remediation chambers 20. Heat sensors and air emission monitoring equipment can employed to maintain environmental compliance and the interior components of the soil remediation chambers 20 can be made of suitable heat resistant materials to ensure proper operation of the equipment.

In yet another aspect of the present invention (not shown), at least one soil remediation chambers 20 is a membrane treatment system such as, but not limited to, a Kenterprise Research, Inc. MLM-20 oil separator as described by James Keane, Membrane-Like-Material A New Approach for Oily Water Treatment Spills Control Management 1996 and incorporated herein by reference.

In yet another aspect of the present invention (not shown), at least one soil remediation chambers 20 is an oxygen treatment system such as, but not limited to, a PermeOx® Solid Peroxygen system made by FMC Corporation as described in PermeOx® Solid Peroxygen Can Enhance Conventional Bioremediation Methods, FMC Corporation 1994 and incorporated herein by reference.

In yet another aspect of the present invention (not shown), at least one soil remediation chamber 20 is equipped with an ultraviolet light source for treatment of contaminates susceptible to ultraviolet light.

In yet another aspect of the present invention (not shown), the track vehicle 200 is equipped with a Ground Penetrating Radar System (GPR) for locating underground utility installations, geologic formations, and debris. In addition, the track vehicle can have magnetic material removal devices, screening, shredding and crushing devices for additional treatment of the soil within the soil remediation chambers 20.

In yet another aspect of the present invention, the present invention 10 including the track vehicle 200 and can be manually operated on-board, remotely operated or configured to automatically operate according to pre-selected parameters stored in an on-board computerized control system.

In another aspect of the present invention as shown in FIG. 6, the multi-section soil remediation device 10 can be attached to an in-situ trenching tool 500 as described in U.S. Pat. No. 5,631,160. FIG. 6 shows the vehicle 200, power source 210 and emission recovery system 310 for operation in cooperation with the trenching tool 500.

The trenching tool 500 penetrates the ground, churns, comminutes, and macerates the soil in situ with a plurality of chain driven carbide-tipped teeth (not shown). A portion of the soil is feed into a soil remediation chambers 20 where a remediation fluid is discharged into the soil as it is conveyed through the remediation chambers 20. In one aspect of the present invention, a screw type conveyer (as shown in FIG. 1) is used which comminutes the soil allowing it to macerate with the treatment fluids which further enhances the extraction of contaminates.

The contaminates are also removed from the soil remediation chambers 20 by a common or additional soil treatment delivery system 40. It is understood that the remediation fluid may include, and is not limited to, decontamination solids, fluids or heated gases such as air as described in greater detail in U.S. Pat. No. 5,631,160.

As shown in FIG. 6, a remediation fluid injection apparatus 40 is mounted to the remediation chambers 20 to inject a remediation fluid and extract contaminants from a portion of the soil provided by the trenching tool 500. The injection apparatus 40 includes a plurality of injectors positioned along the length of the remediation chambers 20. The injectors are supplied with remediation fluid by the emission recovery system 310. This in-situ soil remediation treatment apparatus and procedure is further explained in related U.S. Pat. No. 5,631,160.

It is further contemplated that the multi-chambered apparatus may be used to execute a chemical oxidative remediation scheme, particularly for the degradation of contaminant organic compounds. A preferred method of chemical oxidative remediation incorporates principles of the Fenton's reaction, in which hydroxyl radicals are generated by decomposition of hydrogen peroxide over a ferrous ion catalyst. Hydroxyl radicals, in turn, react with organic compounds and facilitate those compounds' degradation to innocuous compounds, or further to CO₂ and water. Prior art applications of this chemistry include U.S. Pat. Nos. 5,525,008 and 5,611,642.

Chemical oxidative remediation is applicable to saturated or unsaturated soil, sediment, or sludge (collectively, “soil”) contaminated with polychlorinated biphenyls (PCB's), polynuclear aromatic hydrocarbons (PAH's), chlorinated solvents, nitro-aromatic compounds, organic pesticides, mineral oil products, cyanide, and volatile organic compounds (such as gasoline constituents benzene, toluene, ethylbenzene, xylene, etc.). The remediation method using the multi-chambered apparatus is preferably undertaken as follows. The type and concentration of contamination at a target site determines the amount of oxidative treatment reagents that must be employed. A source of ferrous ion (Fe⁺²), such as ferrous sulfate, is then introduced to the contaminated soil.

The ferrous sulfate or other source of ferrous ion can be delivered to the contaminated soil several ways. The ferrous ion source may be applied to the soil surface, then mixed into the soil by the comminuting action of a trenching tool. The ferrous ion source may alternatively be injected into the soil during the trenching operation by such trenching tool as disclosed in U.S. Pat. No. 5,830,752, bearing injection nozzles adjacent the trenching blade to deliver the ferrous ion source. As another alternative, the ferrous ion source may be introduced into the contaminated soil in the first chamber of a multi-section remediation apparatus, such as chamber 20 a of FIG. 1, mounted on a mobile trenching vehicle as shown in FIG. 6.

The pH of the soil should be within the range of about 5 to about 7, and preferably between about 6.0 and 6.5, for a controlled, effective oxidative reaction to occur. Consequently, the pH of the soil is preferably measured after ferrous ion has been introduced. Soil showing higher pH values can be brought into a preferred range by addition of dilute HCl solution or sulfinic acid to the soil. Likewise, soils having a pH below the preferred range can be brought into the preferred range by addition of lime. The pH-adjusting agent (HCl or lime, for example) can be mixed into the soil in the same manner as described for the ferrous ion source, i.e. by trencher or in the next chamber of a multi-section remediation apparatus, such as chamber 20 b of FIG. 1

A source of hydroxyl radicals is then added to the contaminated soil. Aqueous hydrogen peroxide solution is a preferred source of hydroxyl radicals, as is sodium percarbonate. The hydrogen peroxide may be introduced to the soil in any of the ways described for the ferrous ion source, i.e. by trencher or in the next chamber of a multi-section remediation apparatus, such as chamber 20 c of FIG. 1.

The remediation treatment may be done on saturated or unsaturated soils, sediment, or sludge. Dry soils may require that water be added to the soil to promote better reaction conditions.

An important aspect of the remediation treatment is that mechanical agitation is employed to mix the contaminated soil with the remediation reagents and catalysts. Such agitation is accomplished with the trenching tool noted above, or the means for conveying soil within the device of FIGS. 1 or 6.

The advantages of mechanical agitation to promote mixing are several. Comminution of the soil creates better contact between organic compound contaminants, catalyst, and remediation reagent(s) to promote faster reaction rates and increase the likelihood that the degradative reactions will proceed to completion. Secondly, the thorough mixing enabled by mechanical agitation aids in controlling and dissipating then heat generated by the reactions. The oxidative degradation reactions are exothermic; in fact, runaway reactions can result in explosive conditions in the soil. This is a disadvantage of prior art remediation schemes that rely solely on the advective effects of groundwater to transport remediation reagents to contaminants in the soil or groundwater. Comminuting the soil breaks up dense soils such as clays and produces fissures in the soil that increase air circulation to carry off heat. This promotes better heat transfer, and results in safer operating conditions.

As noted, the device described in FIGS. 1 and 6 may serve as a tool for undertaking the method described above. Further, a single chamber mobile device may be adapted to employ the remediation method of the invention. In a preferred embodiment, the multi-section soil remediation device of FIG. 6 is employed. In such embodiment, contaminated soil is removed from the ground via a trenching tool 500 and fed into a first soil remediation chamber 20 a, wherein a ferrous ion source such as ferrous sulfate is discharged into the soil via soil treatment delivery system 40 as it is conveyed through the remediation chamber. i.e. by trencher or in the next chamber of a multi-section remediation apparatus, such as chamber 20 b of FIG. 1. The soil then passes to a second remediation chamber 20 b, wherein a pH-adjusting agent is introduced, if necessary, via injection apparatus 40. The soil then moves to a third remediation chamber 20 c, wherein hydrogen peroxide is introduced to the soil via injection apparatus 40.

The conveyance mechanism in the soil remediation chambers is preferably a screw-type conveyor 80 to provide the mechanical agitation to promote mixing in the soil. A rotating drum may also be used to effectuate the necessary mixing. Temperature sensors (not shown) can provide feedback to the operators on the extent of the degradation reaction. The treated soil is then returned to the ground.

It will be appreciated that the present invention provides a highly flexible, highly adaptable soil remediation system which enables rapid and adaptable treatment of contaminated materials. In addition, the invention's multi-section construction greatly reduces complexity and cost of the equipment while providing greater efficiency and productivity. These and other advantages of the present invention will be apparent to those skilled in the art from the foregoing specification.

The present invention may be embodied in other specific forms without departing from the spirit or essential attributes thereof and, accordingly, reference should be made to the appended claims, rather than to the foregoing specification, as indicating the scope of the invention. 

What is claimed is:
 1. A method of treating soil, sediment, or sludge contaminated with organic compounds, the method comprising the steps of: (a) introducing a source of ferrous (Fe⁺²) ion to the soil; (b) mechanically agitating the soil of step (a) so that the ferrous ion source becomes mixed in the soil; (c) measuring the pH of the soil resulting from step (b); (d) adjusting the pH of the soil of step (b), if necessary, to a pH in the range of 5-7 by adding a pH-adjusting agent to the soil; (e) introducing hydrogen peroxide to the soil resulting from steps (b) or (d); and (f) mechanically agitating the soil resulting from step (e).
 2. The method of claim 1, wherein the source of ferrous ion is ferrous sulphate.
 3. A method of treating soil, sediment, or sludge contaminated with organic compounds, the method comprising the steps of: (a) introducing a source of ferrous (Fe+2) ion to the soil; (b) mechanically agitating the soil of step (a) so that the ferrous ion source becomes mixed in the soil; (c) measuring the pH of the soil resulting from step (b); (d) adjusting the pH of the soil of step (b), if necessary, to a pH in the range of 5-7 by adding a pH-adjusting agent to the soil; (e) introducing sodium percarbonate to the soil resulting from steps (b) or (d); and (f) mechanically agitating the soil resulting from step (e).
 4. The method of claim 1, wherein the soil is initially excavated from the ground, steps (a), (b), (c), (d), (e) and (f) take place in an ex-situ operation, and the soil resulting from step (f) is returned to the ground. 